> I can see that wines were coming in from other parts of the Soviet union. but South Africa?
Aha, so the cracks even begin to appear in the narrative of the dedicated bulgaro-afrikaner shill! Yes that's right, your cover is blown, I'm onto you.
Errr... As /u/thefoolwhofollowshim notes, at the time the South Africans were being crippled by worldwide boycotts, sanctions and embargoes. But only 'worldwide' in the sense that nobody wanted to get caught, not out of any genuine sense of solidarity.
Everything had to be done under-the-table, and therefore at reduced price. Which was convenient because the Bulgarians wanted to buy cheap, and under-the-table.
I mean, we later found out the South Africans were secretly cooperating with the Israelis to develop their nuclear weapons, is it so absurd they would also secretly cooperate with the Bulgarians to develop a reasonably priced Cabernet Sauvignon?*
* ^(OK fine, there isn't really have any actual evidence of this. But if there was any evidence, it wouldn't be a conspiracy theory would it?)
There's a book about the relationship "The Unspoken Alliance: Israel's Secret Relationship with Apartheid South Africa"
https://www.amazon.com/Unspoken-Alliance-Israels-Relationship-Apartheid/dp/0307388506